CVE-2018-16429 in glib
Summary
by MITRE
GNOME GLib 2.56.1 has an out-of-bounds read vulnerability in g_markup_parse_context_parse() in gmarkup.c, related to utf8_str().
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Analysis
by VulDB Data Team • 05/06/2023
The vulnerability identified as CVE-2018-16429 represents a critical out-of-bounds read condition within the GNOME GLib library version 2.56.1, specifically affecting the g_markup_parse_context_parse() function in gmarkup.c. This flaw occurs during the processing of UTF-8 encoded strings through the utf8_str() function, creating a scenario where memory access violations can occur when parsing malformed markup data. The issue stems from insufficient bounds checking during the parsing of UTF-8 character sequences, allowing attackers to potentially read memory locations beyond the intended buffer boundaries.
The technical implementation of this vulnerability involves the manipulation of UTF-8 encoded markup data that the GLib library processes for various applications within the GNOME desktop environment. When the g_markup_parse_context_parse() function encounters malformed or specially crafted UTF-8 sequences, the utf8_str() processing routine fails to properly validate the byte boundaries of multi-byte UTF-8 characters. This deficiency enables an attacker to construct malicious input that triggers memory access patterns extending beyond allocated buffer limits, potentially exposing sensitive data or causing application crashes.
From an operational perspective, this vulnerability poses significant risks to systems utilizing GNOME GLib 2.56.1, particularly those handling untrusted markup data from web sources, user inputs, or file processing operations. The out-of-bounds read can lead to information disclosure, application instability, or potentially serve as a precursor for more severe exploitation techniques. Applications built on or using GLib 2.56.1, including various GNOME desktop applications, web browsers, and system utilities, could be vulnerable to remote code execution or information leakage attacks if they process untrusted markup content without proper input sanitization.
The vulnerability aligns with CWE-125, which describes out-of-bounds read conditions in software implementations, and can be mapped to ATT&CK technique T1059.007 for command and scripting interpreter usage in exploitation contexts. Security practitioners should prioritize patching affected systems with GLib 2.56.2 or later versions that contain the necessary bounds checking fixes. Additionally, input validation measures should be implemented at application layers to sanitize markup data before processing, and runtime monitoring should be employed to detect anomalous memory access patterns. Organizations should also consider implementing network segmentation and access controls to limit exposure of vulnerable applications to untrusted data sources. The fix typically involves strengthening the UTF-8 validation logic within the parsing context to ensure proper boundary checking during character sequence processing, thereby preventing the exploitation of memory access violations that could otherwise compromise system integrity and confidentiality.